RFR: 8180352: Add Stream.toList() method

[Martin Desruisseaux]

Le 06/11/2020 à 19:00, Alan Snyder a écrit :
> (…snip…) But a question that deserves ongoing review is whether Java 
> should support immutable collections using a separate type hierarchy 
> (…snip…).

Maybe an alternative way (admittedly more difficult) to have immutable 
collections without introducing new interfaces could be to take 
inspiration from the C++ "const" keyword? Especially since in Java, 
"const" is already a reserved keyword, just not used yet.

I realize that it would be a difficult task: how to handle private 
fields that are just caches in a const object; where to add the "const" 
keyword in existing JDK API; how to make such change in a backward 
compatible way (e.g. when a legacy code overrides a "const" method). I 
do not have any expectation. But given the inconvenient of alternatives, 
I wonder if there is some research about the long-term feasibility of a 
"const" semantic in Java? If it was the case, then maybe it would be 
better to not add immutable collection interfaces in Java for now.

     Regards

         Martin